In the manufacture of pneumatic tubeless radial tires, reinforcing fabrics are utilized in order to get the desired properties in the final tire construction. The reinforcing fabrics are alternatively referred to as the carcass fabric, cord fabric, or ply fabric. Such fabrics typically have a number of large denier yarns extending in one direction (e.g. the warp direction), the yarns being held only loosely together, for example by widely spaced small denier weft yarns interwoven with the warp yarns. The fabric is tackified, as by calendering it with rubber, so that it will properly adhere to unvulcanized vulcanizable rubber during the construction of the tire. The sidewalls, any reinforcing belts (such as fiberglass belts), and tread portion of the tire are then disposed on or formed around the carcass fabric.
During tire building, the free ends of the carcass fabric are joined together at a particular circumferential portion surrounding a rubber inner lining body of the tire. Typically the free ends of the carcass fabric are merely butted up against each other. Since the carcass fabric is not secured during tire building, oftentimes the free ends separate, resulting in a blemish due to the recess or valley formed at the point of separation, on the sidewall of the tire. Many conventional woven and knitted tire fabrics have been evaluated without successfully remedying this problem.
According to the present invention, a method is provided for splicing together the ends of the carcass fabric so that separation of the ends of the carcass fabric, with ensuing blemish, does not result. This desirable result also is achieved without requiring overlapping of the end portions of the carcass fabric, which itself may produce undesirable results in the final tire.
According to the method of the present invention, the carcass fabric is wrapped around a rubber inner lining body, with turned up portions of the carcass fabric at a pair of beads on opposite sides of the body, during tire construction, as is conventional. The free ends of the carcass fabric are butted together around the body to provide a butt seam, also as conventional. The free ends of the carcass fabric are held together in butting position by placing an open mesh warp knit splicer fabric, one that is highly extensible in both the machine and cross-machine directions, over the butt seam and affixing the splicer fabric in place. The splicer fabric is preferably held in place by an adhesive. The open mesh warp knit fabric according to the invention appears to have no machine direction or crossmachine direction yarns, but only bias yarns. Although the actual fabric does have two sets of warps (machine directions yarns) which are distended in the cross machine direction when the fabric is finished yielding a bias appearance. This is necessary in order to get the extensibility, conformity, and strike through properties desired for the splicer fabric. Typically the warp knit fabric is a two bar partially threaded warp knit mesh fabric whereby the threading is one in, one out, on both the back guide bar and the front guide bar.
The invention also contemplates a pneumatic tubeless radial tire which is constructed utilizing the butt seam between the carcass fabric ends, with the open mesh splicer fabric according to the invention adhesively secured in place over the butt seam to the carcass fabric. The tire according to the invention will not have blemishes in the sidewalls thereof due to a recess or valley formed as a result of separation of the carcass fabric, nor will there be like surface imperfections due to overlapping of the carcass fabric ends.
It is the primary object of the present invention to provide a method of splicing together the ends of a carcass fabric during the building of a pneumatic tubeless tire which substantially eliminates blemishes in the sidewalls of tires produced, and the blemish-free tires produced according to the method. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.